Apparatus for producing flakes of nickel



Jan. 13, 1970 ENORDBLOM ET AL 3,489,666

APPARATUS FOR PRODUCING FLAKES 0F NICKEL Original Filed Feb. 18, 1966United States Patent 3,489,666 APPARATUS FOR PRODUCING FLAKES OF NICKELGeorge F. Nordblom, Yardley, and George W. Bodamer, Cheltenham, Pa.,assignors, by mesne assignments, to ESB Incorporated, Philadelphia, Pa.,a corporation of Delaware I Original application Feb. 18, 1966, Ser. No.528,429, now Patent No. 3,414,486, dated Dec. 3, 1968. Divided and thisapplication July 12, 1968, Ser. No. 754,519

Int. Cl. BOlk 3/02; C23b 7/08 US. Cl. 204-208 9 Claims ABSTRACT OF THEDISCLOSURE An apparatus used to produce small flakes of metallic nickelabout inch square and about 0.000040 inch thick comprises: a cylindricalcathode at least partially disposed in an electrolyte bath contaningnickel ions; a belt made from an electrically non-conducting materialand divided into grids about inch square, the gridded belt beingarranged to engage at least a portion of the cathode surface disposed inthe electrolyte bath; an anode disposed in an electrolyte bathcontaining nickel ions; a arranged to conduct current through theelectrolyte bath between the cathode and the anode; and means fordirecting a stream of fluid at the cathode to remove the nickel flakes.The belt may be wrapped entirely around the cylindrical cathode, or itmay be wrapped only partially around the cathode with the remainder ofthe belt engaging pulleys; in the latter instance the cathode may havegrooves to engage the belt in sprocket-aud-chain fashion.

This invention is a division of copending application of George F.Nordblom and George W. Bodarner, Ser. No. 528,429, filed Feb. 18, 1966,entitled Method for Producing Flakes of Nickel.

This invention relates to a method of producing flakes of nickel, and tothe apparatus used to produce the flakes.

This invention is related to one disclosed in another application filedon the same date as this one, in which George F. Nordblom, one of theapplicants herein, is the applicant.

Small flakes of metallic nickel, about inch square and about 0,000040inch thick, are usually packed in the tubular positive plates ofnickel-alkaline batteries along with nickel oxyhydrate active materialto increase the conductivity of the positive plates. Since the days ofThomas Edison, these flakes have been produced by electro-depositingnumerous alternate layers of nickel and copper on a cathode inelectrolyte baths to form large sandwiched sheets. The sheets have thenbeen cut into small squares, following which the copper layers weredissolved out, leaving only the tiny nickel flakes. The flakes were thenwashed, dried and Screened before being put into the positive plates ofthe battery. This long-known process has produced flakes which weregenerally satisfactory, but the process was objectionable because it wasexpensive. This old process was characterized by loss of nickel duringthe copper dissolution step, failure of the flakes to become completelyseparated, high copper losses and recovery costs, and cumbersome andexpensive mechanical and electrochemical processes. What has been neededfor many years was a process of making nickel flakes of the desiredshape in which the deposition and subsequent dissolution of copper couldbe eliminated, for both steps were time consuming and the expenseinvolved was great.

It is the object of this invention to provide a process 3,489,666Patented Jan. 13, 1970 by which nickel flakes can be deposited directlyon the cathode, and subsequently be easily removed, and which willproduce flakes suitable for use in nickel-alkaline batteries.

It is a further object of the invention to provide apparatus suitablefor producing nickel flakes.

Methods of producing nickel flakes to be used for other purposes areknown, but the flakes produced by these processes have proved to beunsatisfactory for use in nickel-alkaline batteries. For instance, inUnited States Patent No. 2,365,356, issued on Dec. 19, 1944 to N.Pilling and A. Wesley, there is disclosed a method of producing nickelflakes to be used in paint pigments. In this process a highly straineddeposit of sheet nickel is produced so that the plated nickel will breakup automatically into flakes and slough off the stainless steel cathode.This process has proved to be unsatisfactory for producing flakes forbatteries, because the flakes so produced tend to curl very tightly; tobe satisfactory for use in batteries the flakes must remain essentiallyflat. The flakes produced by this process are also too thick forsatisfactory use in batteries.

This invention involves the use of a perforated or gridded belt madefrom an electrically non-conducting material which is wrapped about atleast a portion of the electrically conducting surface of a cylindricalcathode. Nickel then is deposited on the exposed conducting portions ofthe cathode surface when the cathode is immersed in an electrolytecOntaining nickel ions and a source of electric current is connected tothe cathode. Flakes of nickel form on the exposed areas of the cathodesurface and are subsequently removed from the cathode. As will be shownin greater detail below, several methods of employing the belt with thecylindrical cathode may be used, and also several methods of removingthe flakes are available.

The invention will be explained in greater detail by making reference tothe drawings, in which FIGURE 1 is a cross-sectional view of theapparatus involved in this invention in which the belt is wrappedentirely around the cylindrical cathode;

FIGURE 2 is a cross-sectional view similar to FIGURE 1 but showing thebelt traveling around two idling pulleys and the cathode rather thanbeing wrapped entirely about the cathode; and,

FIGURE 3 is a cross-sectional view similar to FIG- URE 2, but showingthe cathode having grooves to engage the gridded belt insprocket-and-chain fashion.

The cylindrical cathode must be made from a material which will permitthe nickel to be removed from its surface; stainless steel orchrome-plated steel are known to be acceptable materials meeting thisrequirement.

The belt should be made from a material which is electricallynon-conducting, non-reactive with the electrolyte with which it is to beused, capable of being formed into the desired grid shape, andsufliciently elastic to be functional with the other apparatus employed.No doubt there are numerous suitable materials from which the belt couldbe made, with many rubbers being known to be acceptable. This inventionshould not be regarded as being limited to the material from which thebelt is formed.

Likewise, this invention is not to be limited to use with one or moreparticular nickel ion electrolyte baths, for no doubt many solutionscould be found which would be acceptable. A composition which is knownto be satisfactory consists of grams/liter of nickel carbonate, 250grams/liter of sulfamic acid, 25 grams/liter of boric acid, and 37milliliters/liter of an 18% nickel br 'omide solution. Good results wereachieved using this bath at 45 C. using current densities as high as 200amps/square foot, and at 39 C. a current density of 100 amps/square footproved satisfactory. An alternate bath consisting of 30 ounces pergallon of nickel fluorborate containing 7 ounces per gallon of metallicnickel produced good flake when a current density of 85 amps/square footwas used in a bath at 40 C.

The invention likewise is not to be limited to the .manner in which thenickel flakes are removed from the cathode. The preferred method is touse a spray of electrolyte because this is generally satisfactory. Jetsof other fluids can likewise be used where they will not contaminate ordilute the plating bath. The use of magnets to remove the flake isanother possibility, although this too is expensive because of theequipment required. It should be clear, however, that there are severalways by which the nickel flake may be removed, and the choice of whichis to be used depends on economics.

Several methods of employing the belt with the cylindrical cathode maybe used. As shown in FIGURE 1, the belt 1 may be wrapped entirely aroundthe cathode 2. If this is done, it may be helpful to apply a jet 3 ofelectro lyte 4 against the submerged portion of the cathode to removeany hydrogen or other gases which might collect on the cathode betweenthe grids of the belt. A simple jet 5 of electrolyte could be used toremove the flake, as shown in FIGURE 1. Both jets 3 and 5 may besupplied from a common pump '6. An anode 7 is submerged in theelectrolyte 4.

FIGURE 2 depicts the use of a pair of idling pulleys 8 which could beemployed with the belt if desired. Similarly, the cathode 2 could benotched as at 9 to engage the belt in a sprocket-and-chain fashion ifdesired, as shown in FIGURE 3.

Obviously numerous variations embodying our invention are possible, forthe invention may be utilized with a variety of belt materials,electrolyte compositions, and methods of removing the nickel flake. Thebelt may be used with the cathode in several ways. The invention shouldbe viewed in this light.

The nickel flakes produced by any of the .methods described above, whichinvolve depositing nickel on a gridded cathode, have been placed inbatteries and compared with the nickel produced by the old method inwhich copper is first plated in alternate layers with the nickel andthen later dissolved. Flakes produced by the Edison process were packedinto tubes and tamped with a machine having a tamper weighing 1581grams. Alternate layers of active material and nickel flake were packedinto the tube until the tube contained 210 layers of each material. Eachlayer of active material consisted of 0.0326 grams, and the nickel flakecomprised 13.6 percent of the total material introduced into the tube.After being formed against a cadmium negative, the tube was charged at93 milliamps for 16 hours, rested an hour, discharged at 187% milliamps,and run through 16 charge-discharge cycles. The average capacitydeveloped using this Edison-type flake was 0.165 ampere hours/ gram.Utilizing flake produced by the methods described above in which thesulfamate electrolyte was used, this test procedure was repeated, withthe only variation being that the amount of flake used was 13.9 percentof the total; the capacity of this tube was 0.158 ampere hours/ .4 gram.Utilizing flake produced by the methods described above in which thefluoborate electrolyte was used, this test procedure was again repeated,with the amount of flake used being 9.0 percent of the total; thecapacity of this tube was 0.153 ampere hours/ gram. The comparisonswarrant the conclusion that the nickel flakes produced by this inventionare as acceptable as those made by the former method.

Having described our invention so that those skilled in the art mayunderstand it, what we claim is the following:

1. An apparatus for producing flakes of nickel comprising:

(a) means for containing a bath of electrolyte;

(b) a rotatably mounted cylindrical cathode disposed at least partiallywithin the electrolyte bath;

(c) a belt .made from an electrically non-conducting material anddivided into grids, the gridded belt engaging at least a portion of thesurface of the cath ode while that portion of the surface is disposedWithin the electrolyte bath;

(d) an anode disposed within the electrolyte bath;

(e) a source of electric current, arranged to conduct current throughthe electrolyte bath between the cathode and the anode; and,

(f) means for directing a stream of fluid at the oathode to remove thenickel flakes.

2. The apparatus of claim 1 wherein the cathode is stainless steel.

3. The apparatus of claim 2 in which the gridded belt is wrappedentirely around the cylindrical cathode.

4. The apparatus of claim 2 in combination with a pulley, the griddedbelt engaging both the cathode and the pulley.

5. The apparatus of claim 4 in which the cathode has grooves to engagethe belt in sprocket-and-chain fashion.

6. The apparatus of claim 1 wherein the surface of the cathode ischrome-plated.

7. The apparatus of claim 6 in which the gridded belt is wrappedentirely around the cylindrical cathode.

8. The apparatus of claim 6 in combination with a pulley, the griddedbelt engaging both the cathode and the pulley.

9. The apparatus of claim 8 in Which the cathode has grooves to engagethe belt in sprocket-in-chain fashion.

References Cited UNITED STATES PATENTS 2,773,816 12/1956 Wesley et al20412 2,429,902 10/1947 Sternfels 204216 3,002,898 10/1961 Jarvis 204-10FOREIGN PATENTS 1,303,624 8/1962 France.

JOHN H. MACK, Primary Examiner R. L. ANDREWS, Assistant Examiner US. Cl.X.R. 0 r-. .81

